From 43ca4957a15a120d0822a60a22998dbb41bbf075 Mon Sep 17 00:00:00 2001 From: Kautuk Consul Date: Fri, 23 Dec 2011 16:52:42 +0530 Subject: [PATCH] MIPS: fault.c: Port OOM changes to do_page_fault Commit d065bd810b6deb67d4897a14bfe21f8eb526ba99 (mm: retry page fault when blocking on disk transfer) and commit 37b23e0525d393d48a7d59f870b3bc061a30ccdb (x86,mm: make pagefault killable) The above commits introduced changes into the x86 pagefault handler for making the page fault handler retryable as well as killable. These changes reduce the mmap_sem hold time, which is crucial during OOM killer invocation. Port these changes to MIPS. Without these changes, my MIPS board encounters many hang and livelock scenarios. After applying this patch, OOM feature performance improves according to my testing. Signed-off-by: Mohd. Faris Signed-off-by: Kautuk Consul Cc: Ingo Molnar Cc: Peter Zijlstra Cc: linux-mips@linux-mips.org Cc: linux-kernel@vger.kernel.org Patchwork: https://patchwork.linux-mips.org/patch/3217/ Signed-off-by: Ralf Baechle --- arch/mips/mm/fault.c | 36 +++++++++++++++++++++++++++++------- 1 file changed, 29 insertions(+), 7 deletions(-) diff --git a/arch/mips/mm/fault.c b/arch/mips/mm/fault.c index 937cf3368164..69ebd586d7ff 100644 --- a/arch/mips/mm/fault.c +++ b/arch/mips/mm/fault.c @@ -42,6 +42,8 @@ asmlinkage void __kprobes do_page_fault(struct pt_regs *regs, unsigned long writ const int field = sizeof(unsigned long) * 2; siginfo_t info; int fault; + unsigned int flags = FAULT_FLAG_ALLOW_RETRY | FAULT_FLAG_KILLABLE | + (write ? FAULT_FLAG_WRITE : 0); #if 0 printk("Cpu%d[%s:%d:%0*lx:%ld:%0*lx]\n", raw_smp_processor_id(), @@ -91,6 +93,7 @@ asmlinkage void __kprobes do_page_fault(struct pt_regs *regs, unsigned long writ if (in_atomic() || !mm) goto bad_area_nosemaphore; +retry: down_read(&mm->mmap_sem); vma = find_vma(mm, address); if (!vma) @@ -144,7 +147,11 @@ good_area: * make sure we exit gracefully rather than endlessly redo * the fault. */ - fault = handle_mm_fault(mm, vma, address, write ? FAULT_FLAG_WRITE : 0); + fault = handle_mm_fault(mm, vma, address, flags); + + if ((fault & VM_FAULT_RETRY) && fatal_signal_pending(current)) + return; + perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS, 1, regs, address); if (unlikely(fault & VM_FAULT_ERROR)) { if (fault & VM_FAULT_OOM) @@ -153,12 +160,27 @@ good_area: goto do_sigbus; BUG(); } - if (fault & VM_FAULT_MAJOR) { - perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS_MAJ, 1, regs, address); - tsk->maj_flt++; - } else { - perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS_MIN, 1, regs, address); - tsk->min_flt++; + if (flags & FAULT_FLAG_ALLOW_RETRY) { + if (fault & VM_FAULT_MAJOR) { + perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS_MAJ, 1, + regs, address); + tsk->maj_flt++; + } else { + perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS_MIN, 1, + regs, address); + tsk->min_flt++; + } + if (fault & VM_FAULT_RETRY) { + flags &= ~FAULT_FLAG_ALLOW_RETRY; + + /* + * No need to up_read(&mm->mmap_sem) as we would + * have already released it in __lock_page_or_retry + * in mm/filemap.c. + */ + + goto retry; + } } up_read(&mm->mmap_sem);